Talk:Cell Division

From CellBiology


  • RNA Granules in Germ Cells
  • “Germ granules” are cytoplasmic, nonmembrane-bound organelles unique to germline.
  • germ granules appear as dense, fibrillar structures that in some cases appear to have distinct subcompartments
  • Balbiani bodies, consisting of ER and mitochondria interspersed with nuage surrounding Golgi stacks
  • During meiosis, spermatocytes assemble a unique type of germ granule called the chromatoid body
  • Two main classes of cytoplasmic RNA granules have been described in somatic cells: processing bodies and stress granules (Balagopal and Parker 2009). Processing bodies (P bodies) and stress granules share components implicated in RNA storage, turnover, and translational regulation.
  • germ granules might correspond to P bodies and/or stress granules
  • Germ granules have also been implicated in the regulation of mRNA levels, by promoting either mRNA storage or mRNA turnover at specific developmental stages.

Cytoplasmic RNA granules in somatic cells - share components implicated in RNA storage, turnover, and translational regulation.

  1. Processing bodies - (P bodies) contain components of the mRNA decay machinery,
  2. Stress granules - contain TIA proteins, poly-A binding protein, and stalled translation initiation complexes

Biol Reprod. 1970 Feb;2(1):129-53. Observations on the fine structure and relationships of the chromatoid body in mammalian spermatogenesis. Fawcett DW, Eddy EM, Phillips DM. PMID 4106274

  • chromatoid body relocalizes to the base of the flagellum in elongating spermatids (Fig. 2C), and disassembles later during spermatogenesis

  • Nuage (or commonly known as chromatoid body in mammals) is a conserved germline-specific organelle that has been linked to the Piwi-interacting RNA (piRNA) pathway.
  • Vasa (known as Mouse Vasa Homolog in mouse), a nuage component, plays a mitotic role in promoting chromosome condensation and segregation by facilitating robust chromosomal localization of condensin I in the Drosophila germline.

  • Yeast
  • activator proteins called Cdc20 and Cdh1 are required for both APC/C activation and substrate selection
  • APC/C mediated proteolysis of key regulatory proteins drives the cell from G2 through M phase into G1
  • To enter the meiotic program, cells exit the cell cycle early in G1 before the accumulation of the G1 cyclins


Nature Mitosis and Cell Division

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